如何在excel表格中获取已占用单元格的范围

I use C# to automate an excel file. I was able to get the workbook and the sheets it contains. If for example I have in sheet1 two cols and 5 rows. I wanted o get the range for the occupied cells as A1:B5. I tried the following code but it did not give the correct result. the columns # and row # were much bigger and the cells were empty as well. I use C# to automate an excel file. I was able